The present invention refers to a locking device intended as a fastening element for prostheses, such as leg- or arm prostheses, of the kind in which the prosthesis is to be attached to a cylindrical member such as a pin, an axle, a tube or the like, said locking device comprises a housing with a through opening for receiving said pin or the like and a locking mechanism arranged therein for locking to the pin in one axial direction thereof, and said locking device further comprising activating means for activating and releasing the grip of the locking mechanism to the pin.
The locking device can for example be used in such cases where a silicone stocking has been threaded on the arm- or leg stump, said silicone stocking in its bottom part having a plastic cup moulded thereto and said plastic cup having a pin attached thereto. The leg- or arm stump provided with the silicone stocking is inserted into a prosthesis sleeve attached to the prosthesis, said sleeve being provided with a locking device for the pin.
In the international patent application WO 94/04101 there is shown a fastening means intended for a prosthesis, said fastening means being in the form of an inclined washer which by spring force is kept in an inclined position and in this position locks to the pin. The inclination of the washer can be reduced by means of an actuating means, at which the locking to the pin is released.
In the international patent application WO 99/32056 there is shown a locking device for a prosthesis comprising a holder with a ring of balls arranged therein, which by spring action is pressed into a conical seat, at which it is locked to the pin. The ring of balls can be released from the conical seat by means of actuating means.
These locking devices per se function well, but it can sometimes be difficult for the prosthesis wearer to with his own force bring the pin with the silicone stocking and stump connected thereto sufficiently deep enough into the locking device attached to the prosthesis sleeve. This problem can for example occur due to a large amount of soft parts on the arm- or leg stump. The consequence will be instability and a so called pump effect, which means that the prosthesis is displaced up and down on the leg stump for each step that is taken. The risk for stumbling increases since the prosthesis consequently slides down on the leg stump when the prosthesis is lifted from the floor. Injurious compensating behaviour can then occur, for example by lifting the leg higher by means of the hip and raising on tiptoe with the healthy foot in order to get free from the ground.
The object of the present invention is to provide a locking device of the kind mentioned above, which in an effective way helps the prosthesis wearer to pull the pin and by that the silicone stocking/body part deeper into the prosthesis sleeve/locking device. This has been provided by the fact that in the housing along the opening opposite the locking mechanism there is further arranged a gripping member in the form of a spring-loaded washer with a through opening which is somewhat larger than the diameter of the pin and which by means of actuating means can be brought to a tilted position and grip the pin and by that pull this further into the locking device.
Further features of the invention are understood from the following description and the dependant claims.